1. Technical Field
The present invention relates to cutting articles by use of a rotating axially moving tool and more particularly to cutting tools having a work-engaging structure and angled or stepped cutting edges. Still more particularly, the present invention relates to cutting plastic pipe to enable a lateral pipe to be replaced on a Y-connection, a T-connection or a 90xc2x0 connection.
2. Background Information
The prior art discloses various tools and methods for cutting pipe.
U.S. Pat. No. 3,752,592 to Fitzgerald, et al., for example, discloses a pipe reamer apparatus particularly for use with plastic pipe and a method of reaming plastic pipe fittings such as elbows or the like.
U.S. Pat. No. 3,872,748 to Bjalme, el al. discloses a tool for beveling plastic pipe in which the tool is carried in a slide inclined at the bevel angle and fed toward the pipe end as it is rotated about the axis of the pipe.
U.S. Pat. No. 4,483,222 to Davis discloses a device for removing pipe attached to a fitting includes cutting apparatus for removing the pipe disposed within the fitting. A wrench apparatus is connected to the cutting apparatus for gripping the fitting to prevent its movement when the cutting apparatus is activated. Alternatively, this device may be used as a reaming device which permits radial movement of the cutting blades into engagement with a pipe after the cutting blades have been inserted within the pipe.
U.S. Pat. No. 4,693,643 to Heyworth discloses a planing device which is operable for progressively planing or cutting the end of a plastic pipe to the desired length, or for reaming out a piece of plastic pipe fixed in a plastic pipe fitting in such a manner that the plastic pipe fitting can be reused. The pipe planing device is portable and is rotated by an electric drill or the like and includes a cylindrical pilot removably supported on radially spaced-apart spider-like cutter arms having cutter blades attached to their outer ends and extending outwardly beyond the cylindrical pilot distance which is equal to the thickness of the plastic pipe to be cut or reamed. The outer circumference of the cylindrical pilot is dimensioned to provide a snug rotatable fit within the end of the plastic pipe to be planed and operates to center the planing device along the longitudinal axis of the plastic pipe.
U.S. Pat. No. 4,975,001 to Rabo, et al. discloses a plastic pipe reboring tool having an elongated shank, a generally concave-convex cutting head, and changeable guide discs effective for cleaning residue glue and plastic from used plastic pipe and fittings so they can be used over again. The reboring tool is operational with both powered and manual chuck rotating devices and can be used on different sizes of plastic pipe.
U.S. Pat. No. 5,000,629 to Nygards discloses a self-centering plastic pipe router tool for routing of a sawed-off end of pipe from the interior surface of a salvageable pipe. The router tool is a disk with an axial shank on one side of the disk. A pair of cutting flanges extend radially outwardly and upwardly in the direction of the axial shank form the disk perimeter to form first and second cutting edges. A concentric cylindrical skirt extends downwardly form the disk for axial centering of the router tool within the waste pipe inner diameter. The first cutting edges are sized for routing of the waste pipe and second cutting edges are sized to plane and refinish the interior surface of the salvageable pipe for re-use.
U.S. Pat. No. 5,401,126 to Norris, et al. discloses a bit usable in combination with a rotatory diver, such as a drill, for extracting a remnant of a cut-off pipe from a pipe socket. The bit comprises a forward portion which is a pilot to keep the bit centered in the remnant and thereby centered in the pipe socket, a forward-facing ring cutter whose inner and outer diameters generally match the inner and out diameters of the pipe remnant being extracted, said ring cutter bing operable to cut and/or scrape the remnant edgewise form the socket, and a forward facing ring scraper operable to stop the bit from excessive penetration into the pipe socket and operable to scrape bonding material remnants form the end face of the pipe coupling.
In working with plastic pipe, a relatively common procedure involves replacing a lateral line which extends at a Y-connection, a T-connection or 90xc2x0 connection at a at a main pipe line. This procedure is relatively time and labor intensive and an improved means of carrying this procedure out is needed.
It is an object of the present invention to provide an improved apparatus and method for replacing a lateral line which extends from a Y-connection, a T-connection or a 90xc2x0 connection at a main pipe line.
This and other objects are met by the present invention which is a tool for cutting a plastic pipe comprising a concave guide section having a central aperture. A plunger having a longitudinal axis extends through the central aperture and at least one blade extends in generally radial relation from the central axis inside the lower concave skirt section.
In another embodiment the present invention is a tool for cutting a plastic pipe comprising a concave guide section comprising a lower skirt comprising an upper generally horizontal member and a lower peripheral wall member. There is an aperture in said upper horizontal member and a tubular section having an upper and a lower terminal end and an interior axial passageway and is positioned at said lower terminal end such that said axial passageway is aligned with the central aperture of the generally horizontal member of the lower skirt section. A plunger comprising an upper rod having an upper and a lower terminal end and a spiring retaining structure adjacent said upper terminal end and is disposed in said axial passageway of the tubular member of the concave guide section in coaxial relation with said tubular member and is positioned such that said upper terminal end is elevated above the upper terminal end of the tubular member. A lower blade retaining structure is formed in which at least one blade having a distal edge extends in a generally radial direction such that said distal edge is positioned in spaced inward relation from the lower peripheral wall member of the concave guide section. A helical spring having an upper terminal end and a lower terminal end and coaxially overlaps the upper rod member and bears against the spring returning structure of the rod member at its upper end and bears against the upper terminal end of tubular member at its lower end.
Also encompassed by the present invention is a method for replacing a first lateral pipe with a second lateral pipe when the first lateral pipe is connected to a main pipe line by a Y-connection, a T-connection or a 90xc2x0 connection. In this method the first lateral pipe is cut outwardly from the widened connection socket on the Y-connection, a T-connection or a 90xc2x0 connection. A tool as is described above is then positioned reality to the widened connection section so that the inner surface of the concave guide section bears against the outer surface of widened lateral connecting section and distal edge of the blade bears against the first lateral pipe section. The plunger is then rotated about it longitudinal axis so that the blade cuts away at least part of the inner first lateral pipe section to form a pipe receiving space adjacent the widened connection socket. A second lateral pipe is then inserted end wise into the pipe receiving space to complete the procedure.